Sound Track: Audio-torium

How to get good audio from auditoriums, gyms and other sound-hostile environments.

As anyone who has tried to record audio in an auditorium can tell you, large enclosed spaces with smooth, reflective surfaces can be a videographer's worst nightmare. Sounds careen off the hard walls, floor and ceiling of a gym, theatre or music hall for many seconds before they're finally absorbed, blending and combining to create a symphony of noise.

For those of you who need to record coherent, understandable sound from auditoriums and gyms, here are 10 tips to help insure success.

1. Get Close
   The old standby advice for getting clean audio from hostile environments holds doubly true for auditoriums and gyms. Like trying to shoot video in pea-soup fog, your main hope for clean audio from a highly reverberant location is to get your camcorder as close to your subject as possible. This makes the sound you're trying to record much louder as compared with the competing noises.

   If you're shooting a game-side interview or a speaker addressing a room full of listeners, don't plan on getting clean audio from across the room. Move your camcorder as close as possible to the sound source. Because of the way sound travels through air, cutting the distance between camcorder and subject doesn't make the subject twice as loud--it makes it four times as loud.

2. Use an External Mike
   There are some obvious limits to how close you can move your camcorder to your subject when shooting in a noisy environment. Attach an external mike to your camcorder, and you can close the gap to within a few inches. Lavalier mikes offer the advantage of hands-free communication, while a handheld mike allows you to move quicker and is more comfortable for some people.

   Wired external mikes offer the advantage of a relatively foolproof link between mike and camcorder, but the dangling cable can restrict mobility somewhat. Wireless lav or handheld mikes offer great freedom of movement, but can be prone to poor reception and interference when used indoors. On the plus side of the wireless equation, they work well when you have short distances between the mike and receiver.

3. Pick a Quieter Locale
   Perhaps the most effective way to get good audio from a gym or auditorium is to flee the premises altogether. If you're conducting an interview with a coach, player or excited fan, for example, there's no rule that says you have to do it in the middle of the post-game furor.

   You'll probably get much better sound from the locker room, a hallway, or any other room located near the gym. Staying close to the auditorium insures that the viewer will still hear and/or see the excitement of the event. You may get great audio and a neat visual effect by staging an interview just outside the doors of the gym, pointing the camcorder back in towards the victory celebration.

4. Move Within the Room
   Even without leaving the room, you may be able to find a location more conducive to capturing clean audio (provided you can move your subject). As sound bounces around a large room, there are areas where the noise is less pronounced. Recording in the corner of a room, for example, may result in cleaner sound. Recording in an area with sound treatment panels or heavy curtains on the walls should also cut down on ambient sound.

   If you can move behind some obstruction, you may get cleaner audio as well. This might mean staging an interview behind a divider of some kind, or in back of a row of folded bleachers or stacked chairs. With careful framing, viewers will never know you're shooting from behind a sonic barricade.

5. Wait for Less Noise
   In the same way you don't necessarily have to shoot right in the middle of a post-game celebration, you may not need to shoot at a time when the gym or auditorium is at its noisiest. Try to get a speaker or presenter into the auditorium before a big event, to conduct an interview while the stage and sound system are being set up. Or, you may capture a completely different feeling by talking with a winning coach in the gym after all the fans have left. You'll still have some reverberant sound bouncing around the room from your subject, so you'll probably want to use an external mike.

   Overcoming bad sound from an auditorium or gym is not just a matter of the right equipment--a little creative thought put into the where and when of your shoot can make a large difference in the quality of the resulting audio.

6. Tap Into the House Mixer
   Many venues will have a "house" sound system used for amplifying the voice of a speaker or sports announcer. If you can borrow an audio signal from this mixer, you may get excellent audio quality. Balanced audio is best for long cable runs, and you can convert the more-common unbalanced mixer output to a balanced line with a transformer. Another option is to plug a wireless transmitter into the house mixer and send the signal to your camcorder.

   Wiring into an existing mixer successfully requires either a good knowledge of signals and connectors on your part, or a good relationship with the (hopefully) knowledgeable sound person. At the very least, have a good stock of adapters, transformers and attenuators on-hand. The better prepared you are, and the easier you are to work with, the better your chances of getting a clean audio feed. Finally, be sure to use headphones to monitor the house feed at your camcorder. Should something go wrong with the signal, be ready to unplug your input cable and switch over to the camcorder's built-in mike at a moment's notice.

7. Mike the Announcer or Speaker Yourself
   One effective alternative to wiring into a mixer is to mike the announcer or speaker yourself. You may be able to attach a wireless lavalier mike directly to the person who will be speaking, provided you don't interfere with his or her mobility. A more likely prospect is to place a mike on a small stand on the table or podium. You'll get clean, up-close audio from this approach, and may experience fewer hassles than tapping into the house sound system.

   Clearly, using your own mike in this way requires securing permission in advance. Because some may perceive the potential for problems when you add your own mike to the equation, don't get your heart set on this approach. When you do get the green light to use your own mike, the result is often excellent sound.

8. Make Friends with the Loudspeaker
   If you can't tap into the sound system or mike the announcer yourself, get a mike as close as possible to a loudspeaker. This approach will give you good sound with less background noise. Setting your camcorder up within ten or 20 feet of a loudspeaker may do the trick. If background sounds are really pronounced, you may want to place an external mike on or near the speaker. You'll get good results from a handheld mike on a stand, pointed at the speaker from a few feet away.

   Another approach is to put a wireless lavalier mike in the vicinity of the speaker. Attaching it directly to the speaker is a tricky proposition, as most loudspeakers consist of two or more drivers each radiating a smaller portion of the audible spectrum. Put your mike too close to one, and you'll get audio with too much bass or too much treble.

9. Use a Shotgun or Parabolic Mike
   The more directional a microphone, the less ambience it picks up at a given mike-to-subject distance. If you can't put a mike on or near your subject, you'll get better results with a highly directional shotgun or parabolic mike. The former will attach to the camcorder, increasing the "range" of your sound pickup.

   A parabolic mike has an even tighter pattern than the shotgun, thanks to its 12- to 18-inch sound-gathering reflector. Unfortunately, parabolic mikes are somewhat hard to come by and can be rather expensive. Remember--getting a less-directional mike close to your subject almost always results in better sound than a more distant pickup with a highly directional mike.

10. Don't Record Dialogue
    For some productions, you may be better off dubbing in your dialogue after-the-fact. This is especially true if you have no external mike and your production calls for long shots. Dialogue recorded from across the gym will net you unusable audio, guaranteed.

    With some careful planning, you can set up wider shots where a small deviation in lip-sync won't be noticeable. Then, after you've shot all your footage, have your talent speak their lines in a more acoustically controlled place. The resulting dialogue will lack the ambience and echoes the audience will expect to hear, so you'll have to add some ambience back in. Use an audio mixer or an inexpensive effects processor. Simply run the dialogue through a "large room" or "large hall" reverb program, mix in an appropriate amount of the effect, and you'll have realistic ambience and crisp dialogue. You can perform similar acoustic magic with a computer-based system.